Thanks BeatleFred for the additional info. I have contacted OBSInc and a third vendor regarding the service manual, so I'm sure we'll have one fairly soon.

I have cleaned noisy switches, jacks and pots before on my guitars and various tube amps I have owned, so I may try the same with the AU-719. I wonder if that intermittent signal loss/distortion on both channels when it reaches stable operating temperature could be just a cleaning problem? Are there any less obvious relays, etc. not on the front or back panel that should also be done with contact cleaner?

Speaking of cleaning, is there any safe way to remove the greasy 25-year accumulation of dust off circuit boards, etc.? I imagine that some of this dirt could possibly result in conductivity problems as well. Or is this better left to professionals? Take care...I'll try not to bug you again for awhile.

steph

(by the way, I really like the Audio Karma site as well. Nice to know there is a good community of diehard Sansui fans around. I have also owned an AU-101 and still have an AU-555 along with those fantastic SP-5500 speakers, so I guess I'm hooked as well...)